Update nginx from 1.19.1 to 1.19.2.
Update njs module from 0.4.2 to 0.4.3.

While I'm here soften some variables and target definitions to
prepare the port for a separate build of dynamic modules.

<Changelog for nginx 1.19.2>

*) Change: now nginx starts closing keepalive connections before all

free worker connections are exhausted, and logs a warning about this
to the error log.

*) Change: optimization of client request body reading when using

chunked transfer encoding.

*) Bugfix: memory leak if the "ssl_ocsp" directive was used.

*) Bugfix: "zero size buf in output" alerts might appear in logs if a

FastCGI server returned an incorrect response; the bug had appeared
in 1.19.1.

*) Bugfix: a segmentation fault might occur in a worker process if

different large_client_header_buffers sizes were used in different
virtual servers.

*) Bugfix: SSL shutdown might not work.

*) Bugfix: "SSL_shutdown() failed (SSL: ... bad write retry)" messages

might appear in logs.

*) Bugfix: in the ngx_http_slice_module.

*) Bugfix: in the ngx_http_xslt_filter_module.

</Changelog>

<Changelog for njs 0.4.3>

Core:

*) Feature: added Query String module.

*) Feature: improved fs.mkdir() to support recursive directory creation.

Thanks to Artem S. Povalyukhin.

*) Feature: improved fs.rmdir() to support recursive directory removal.

Thanks to Artem S. Povalyukhin.

*) Feature: introduced UTF-8 decoder according to WHATWG encoding spec.

*) Feature: added TextEncoder/TextDecoder implementation.

*) Bugfix: fixed parsing return statement without semicolon.

*) Bugfix: fixed njs_number_to_int32() for big-endian platforms.

*) Bugfix: fixed unit test on big-endian platforms.

*) Bugfix: fixed regexp-literals parsing with '=' characters.

*) Bugfix: fixed pre/post increment/decrement in assignment operations.

</Changelog>